Can link a new activity to an existing constituent by providing a valid constituent id in the ExistingConstituentId property - if you pass any constituent information e.g. last name it will be ignored if the ExistingConstituentId has a value - you will need to perform a separate call to the API to update a constituent

Can create a new constituent and activity at the same time by providing a constituent type plus any other name or contact information you have for the new constituent

If you do not pass in an ActivityDate the current system date will be used

When adding an activity you can add a task linked to the activity to do this you must pass in value at least one of the following TaskDetails, TaskAssignedToEmail, TaskDueDate or TaskCompleted, note that

The TaskAssignedToEmail must be the email address of an existing user to whom the task notification will be sent

If TaskCompleted is true then the task completed date will be set to the current system date

If TaskSendNotification is true and your Donorfy is connected to your email server then a task notification email will be sent to the TaskAssignedToEmail address. If sending the email fails the activity and task will still be added and the message returned will include any error message we received when trying to send the email